Material treating apparatus

ABSTRACT

A NOZZLE ASSEMBLY FOR TREATING MATERIALS BY IMPINGEMENT OF A HIGH VELOCITY GASEOUS MEDIUM COMPRISING A PLENUM CHAMBER AND A GENERALLY TRIANGULARLY SHAPED NOZZLE ATTACHED TO SAID PLENUM CHAMBER AND COMMUNICATING THEREWITH.

Sept. 21, 1971 N. STEELE MATERIAL TREATING APPARATUS Filed April. 4, 1969 2 Sheets-Sheet l United States Patent 3,606,974 MATERIAL TREATING APPARATUS Nelson M. Steele, 1762 Townline Ave., Beloit, Wis. 53511 Filed Apr. 4, 1969, Ser. No. 813,635 Int. Cl. A62c 31/10 U.S. Cl. 239568 Claims ABSTRACT OF THE DISCLOSURE A nozzle assembly for treating materials by impingement of a high velocity gaseous medium comprising a plenum chamber and a generally triangularly shaped nozzle attached to said plenum chamber and communicating therewith.

The present invention relates to material treatment apparatus and more particularly to a nozzle assembly therefor for the projection of high velocity streams of gaseous medium onto the material to be treated. The invention further relates to methods of manufacturing such nozzle assemblies.

It is well known to utilize high velocity streams of gaseous medium issuing from nozzles for drying and other purposes and it is also well known to utilize comparatively large exhaust openings between the nozzles for withdrawing spent gaseous medium from the surface of the material to be treated.

Many arrangements and designs of nozzles and exhaust openings are lacking in two important aspects. First of all, the designs are not clean from an aerodynamic viewpoint thereby resulting in ineflicient operation, and secondly, the designs are costly to manufacture.

It will be appreciated to those skilled in the art that the cost of heating a gaseous medium is rising rapidly and that the need for utmost economy in utilizing the heated medium is becoming more and more acute. The need for reduction in cost of this type of equipment has always been present but difficult to achieve.

It is accordingly an important object of the present invention to provide for a simple, economic and efficient nozzle design.

Another object of the present invention is to provide for a nozzle and exhaust opening assembly or arrangement of optimum aerodynamic design.

A further object of the invention is to provide for a novel and simple method of economically constructing nozzle assemblies which may be arranged in any desired con-figuration in order to accommodate the particular path through which the material to be treated travels.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a nozzle assembly in accordance with the principles of the invention;

FIG. 2 is a cross-sectional view of a nozzle assembly constructed in accordance with the principles of the present invention, and taken along the lines 22 of FIG. 1;

FIG. 3 is a cross-sectional view taken along the lines 33 of FIG. 2; and

FIG. 4 is a side elevational view of a nozzle assembly in accordance with the principles of the invention.

In FIG. 1 of the drawings a drying apparatus is shown in perspective view. The drying apparatus essen- 3,606,974 Patented Sept. 21, 1971 "ice tially comprises a plurality of nozzle assemblies 11 mounted in generally parallel relationship to each other and within an exhaust hood assembly 12 which, for purposes of clarity, is shown in dotted lines. The nozzle assemblies 11 are suitably mounted in spaced apart relationship to the interior of the exhaust hood assembly 12. A gaseous medium supply duct 13 is mounted to the rear of the nozzle assemblies and is in open communication with a chamber 14. The chamber 14 is in open communication with the upper, generally rectangularly shaped portions of each of the nozzle assemblies 11. The plenum chambers 15 are in open communication with the nozzle portions 16 by means of longitudinal openings 17. The exhaust hood assembly 121 completely surrounds the nozzle assemblies but is open at the bottom so as to permit the high velocity gaseous medium to exit from the nozzle portions 16 onto the objects to be treated. An exhaust opening 18 is provided in the top of the exhaust hood assembly 12.

The material to be treated by the gaseous medium issuing from the nozzles 16 is represented by a web 19 moving in the direction of the arrow 20. It should, however, be understood that the present invention is not restricted to the drying of weblike materials but may equally be utilized for the drying of other objects such as painted pottery, corn cobs, and the like. For purposes of simplicity, however, the invention will be primarily de scribed in connection with the drying of a weblike material such as represented by the numeral 19.

As shown in FIG. 1, the nozzle assemblies 11 are spaced a predetermined distance 21 above the web 19. In operation, hot gaseous medium is introduced into the supply duct 13 and enters the plenum chambers 15 of the nozzle assemblies 11 via chamber 14. From the plenum chambers 15 the gaseous medium enters the nozzle portion 16 through openings 17 located in the bottom wall of the plenum chamber. The gaseous medium then exits from the bottom of the nozzles 16 and impinges upon the web 19 substantially as shown by the arrows 22. The spent gaseous medium after impingement on the web 19 is forced to enter into the spaces between the nozzle assemblies 11 as shown by the arrows 23 and is removed from the exhaust hood assembly 12 through exhaust opening 18. The spent gaseous medium from the exhaust opening 18 may, if desired, be dehumidified and reused in order to improve overall etficiency. A suitable damper mechanism, indicated by the numeral 24 may be utilized in connection with the air supply duct 13 in order to regulate the volume of air supplied to the nozzle assemblies 11.

Referring now to FIG. 2 of the drawings, the nozzle assembly 11 is shown in cross-sectional view substantially along the lines 22- of FIG. 1. The nozzle assembly 11 comprises a plenum chamber 15 and a nozzle portion 16. The plenum chamber 15 is in open communication with the nozzle portion 16 by means of openings 17. The plenum chamber 15 is of generally rectangular crosssectional area and may be manufactured from a suitable material such as for example sheet metal or heat resistant plastic.

The cross-sectional area of the plenum chamber 15 has a width generally indicated by X and a height generally indicated by Y. In order to obtain good air flow through the plenum chamber 15 the ratio X :Y is preferably in the neighborhood of 1:1.75. In a typical form of the apparatus of the present invention the width of the plenum chamber X may be two inches while the height Y would be in the order of 3.5 inches.

The nozzle portion 16 of the nozzle assembly 1'1 comprises two fiat plate members 25 and 26 Welded to the bottom wall of the plenum chambers 15 at 27 and 28. A spacer member 29 is mounted a predetermined distance above the tip 30 of the nozzle 16. The spacer member 29 may be in the form of a simple bolt or rivet mounted in such a manner as to maintain a predetermined distance a between the lower portions of the plate 25 and 26 thereby forming a relatively narrow continuous slot at the tip 30 of the nozzle 16.

The location and use of the spacer element 29 is an important part of the present invention. In the prior art it has been common practice to construct nozzles of the type described by spot welding the plates 25 and 26' together at the opening 30. The spot welds are spaced at predetermined intervals and suificient welds are used to insure adequate strength. Spot welds of the aforementioned type are distinctly disadvantageous in that they cause the nozzle opening 30 to warp appreciably, but more importantly, the spot welds at the opening 30 create obstructions to the air flow and cause air flow disturbances which greatly impede the efliciency of the nozzle. Such air flow disturbances at the location of the aforementioned spot welds impede the efficiency of the air flow to such an extent that substantially reduced drying of the material is obtained immediately below the spot weld thus causing severe localized moisture variations with obvious unsatisfactory end results. In order to maintain the construction of the nozzles as economic as possible it has been found desirable to maintain spacer elements at spaced intervals along the length of the nozzle. Elimination of the spacer elements would require substantial reinforcement of the plate members 25 and 26 and greatly increase the cost.

It has been found, however, that an obstruction to the air flow at a point above the nozzle opening 30 does not result in undesirable irregularities in air flow out of the nozzle opening 30 since the air or other medium is given ample opportunity to reform or, in other 'words, the flow disturbance created by the spacer elements is given ample opportunity to dissipate. It has been established that the spacer elements 29 should be located a distance b above the nozzle opening 30 which is at least ten (10) times the width a of the nozzle opening 30.

It has further been found that the triangular shape nozzle 16 can be optimized from the standpoint of flow efficiency by making the ratio of the base X of the triangle to the height Z within the range of from 1 to 1.75.

FIG. 2 also shows an additional nozzle assembly 11 mounted in predetermined spaced apart relation from the nozzle assembly 11. As shown with respect to the nozzle assembly '11 the gaseous medium exits from the nozzle opening 30 as indicated by the arrows 22 onto the surface of the article 19. The spent gaseous medium travels upwardly between the space provided between the nozzle assemblies 11 and 11' as indicated by the arrows 23. It has been found that optimum exhaust of spent gaseous medium may be obtained when the spacing between the plenum chambers 15 of the nozzle assemblies is within the range of /s inch to 71 inch each and preferably approximately A In accordance with the present invention the exhaust openings 31 between the nozzle assembly 11 is unobstructed throughout the full width of the nozzle.

FIG. 3 shows a cross-sectional view taken along the lines 33 of FIG. 2 and for purposes of simplicity FIG. 3 has been drawn on a reduced scale. FIG. 3 shows the location of the openings 17 which permit the gaseous medium to flow from the plenum chamber 15 into the nozzle 16. As previously indicated with respect to FIG. 1 the gaseous medium is introduced into the plenum chamber 15 from one end thereof. The feed end of the plenum chamber is indicated in FIG. 3 by the numeral 40. In order to obtain equal flow of gaseous medium from the plenum chamber 15 into the nozzle 16 the spacing and location of the openings 17 is extremely important. As previously indicated, in order to obtain equal drying rates across the width of material to be treated it is essential to obtain equal velocity flow out of the nozzle opening 30'. With a uniform cross section plenum chamber to which gaseous medium is supplied from one end only the spacing of the openings 17 and their relative size is of critical importance. At the same time, it will be apparent to those skilled in the art that substantial economy of design will be realized with the aforementioned constant cross section desi n.

As shown in FIG. 3 the total length of the nozzle assembly 11 is indicated by L. The total axial length of the openings 17 is represented by L The portion of the plenum chamber ahead of the openings 17 is represented by L while the portion of the plenum chamber immediately following the openings 17 is represented by Lr.

It has been found that if the length Lr immediately following the openings 17 is made too large a dead space will be created immediately ahead of the rear wall 41 of the plenum chamber 15. This dead space will result in substantially impeded airflow out of the nozzle opening 30 at a location below the dead space in the plenum chamber. In order to compensate for this dead space it has been found that the entire group of openings 17 must be shifted towards the rear wall 41 by a distance which has within the range of from 1 to 1.5 inches. In other words, the group of openings '17 whose axial length is represented by L must be positioned with respect to the overall length L of the plenum chamber so that the following equation is satisfied:

Lf-Lr=l to 1.5 inches It has further been found that equal flow of gaseous medium through the entire length of the nozzle opening 30 is obtained when the total length L of the nozzle openings 17 is approximately /2 of the total length L of the plenum chamber. The land areas 42 between the slots 17 are preferably approximately inch long. The length of the slots or openings 17 are equal with the exception that the central slot is approximately 1 inch longer than the remaining slots. This is desirable in order to obtain proper pressure distribution in the nozzle 16.

FIG. 4 shows an elevational view of the nozzle assembly 11. It will be noted that the front portion or front Wall 45 of the plenum chamber 15 has been beveled at an angle of approximately 45 in order to facilitate the entry of air into the plenum chamber in the direction of the arrow 46.

What is claimed is:

1. A nozzle assembly for treating materials by impingement of a high velocity gaseous medium comprising in combination:

(a) walls, including a bottom wall, defining a plenum chamber;

(b) a nozzle attached to said bottom wall, said nozzle comprising two plates converging towards each other in a direction away from said bottom wall, said plates defining a narrow elongate slot of predetermined width at the converging end of said nozzle;

(c) a plurality of elongate openings in said bottom wall of said plenum chamber, said openings providing open communication between said plenum chamber and said nozzle; and

(d) spacer means located a predetermined distance from said elongate slot and attached to each said plates for maintaining a predetermined distance between said plates thereby maintaining the width of said slot constant.

2. The structure of claim 1 wherein said plenum chamber has a uniform rectangular cross-sectional area.

3. The structure of claim 2 wherein the ratio of the base of said triangle to the height of said triangle is within the range of from 1 to 1.75.

4. The structure of claim '1 wherein said distance of said spacer means to said slot is at least ten times the width of said slot.

5 6 5. The structure of claim 1 wherein the axial length of 3,141,194 7/1964 Jester 239594X said elongate opening is approximately /2 of the axial 3,341,354 9/1967 Woods et a1. 239597X length of said plenum chamber. 3,375,981 4/ 1968 Keck 239592X References Cited LLOYD L. KING, Primary Examiner UNITED STATES PATENTS UIS' CL X'R. 2,670,790 3/ 1954 Marble 23959'7 239 594 597 599 2,921,748 1/1960 Kane 239597X 

